Improve capacity handling for `ColliderSet`, `RigidBodySet`. (#726)

These allow an application to reduce the cost of reallocation when
they know that a large number of colliders or rigid bodies will
be created.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/dynamics/rigid_body_set.rs b/src/dynamics/rigid_body_set.rs
index 2ef91be..3145300 100644
--- a/src/dynamics/rigid_body_set.rs
+++ b/src/dynamics/rigid_body_set.rs
@@ -43,6 +43,14 @@ impl RigidBodySet {
         }
     }
 
+    /// Create a new set of rigid bodies, with an initial capacity.
+    pub fn with_capacity(capacity: usize) -> Self {
+        RigidBodySet {
+            bodies: Arena::with_capacity(capacity),
+            modified_bodies: Vec::with_capacity(capacity),
+        }
+    }
+
     pub(crate) fn take_modified(&mut self) -> Vec<RigidBodyHandle> {
         std::mem::take(&mut self.modified_bodies)
     }